Merging two car bumpers
What you suggested is probably the best option. Line up the edge loops, selected the two vertices across from each other and press &quot;m&quot; on your keyboard and select whichever option you wish. &quot;At center&quot; will bring the vertices closer to a midpoint and merge them, &quot;at first will merge them at the location of the first selected, and &quot;at last&quot; will merge them at the location of the last one selected.
If the two parts are from different models though, there is no guarantee that you will have the right number of vertices to merge without messing up the topology, it may be worth it to re-model the smaller piece.